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myronkscottmyronkscott
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Merge pull request #1375 from myronkscott/fix_ring_buffer
Ring buffer has some implementation issues
2 parents 127340b + 66fa9c4 commit 2869e5d

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6 files changed

+333
-25
lines changed

6 files changed

+333
-25
lines changed

‎common/src/main/java/com/tc/net/protocol/tcm/MessageMonitorImpl.java

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@@ -93,6 +93,7 @@ private ScheduledFuture<?> startLogging(final Logger logger, int intervalSeconds
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public void shutdown() {
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currentTask.cancel(true);
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timer.shutdownNow();
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timer.shutdown();
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}
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@Override

‎common/src/main/java/com/tc/util/SimpleRingBuffer.java

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@@ -18,6 +18,7 @@
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package com.tc.util;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.Iterator;
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import java.util.Objects;
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import java.util.stream.Stream;
@@ -37,7 +38,7 @@ public SimpleRingBuffer(int size) {
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}
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public void put(T item) {
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Objects.nonNull(item);
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Objects.requireNonNull(item);
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buffer[head++] = item;
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head = head % buffer.length;
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}
@@ -48,26 +49,35 @@ public Stream<T> stream() {
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@Override
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public Iterator<T> iterator() {
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final Object[] ref = (buffer[head] != null) ? Arrays.copyOf(buffer, buffer.length) : Arrays.copyOf(buffer, head);
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final int end = head % ref.length;
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return new Iterator<T>() {
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private int pos = (end + 1) % ref.length;
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@Override
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public boolean hasNext() {
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return pos != end;
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}
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if (buffer[0] == null) {
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return Collections.emptyIterator();
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} else {
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// there is at least one item in the list;
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// if the list has not wrapped just reference the non-null list
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final Object[] ref = (buffer[head] != null) ? Arrays.copyOf(buffer, buffer.length) : Arrays.copyOf(buffer, head);
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// current head is the oldest item. If the list hasn't wrapped yet, oldest is the first
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final int pivot = head != ref.length ? head : 0;
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@Override
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@SuppressWarnings("unchecked")
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public T next() {
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try {
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return (T)ref[pos++];
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} finally {
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pos = pos % ref.length;
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return new Iterator<T>() {
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private int pos = pivot;
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boolean done = false;
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@Override
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public boolean hasNext() {
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return !done;
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}
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@Override
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@SuppressWarnings("unchecked")
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public T next() {
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try {
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return (T)ref[pos++];
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} finally {
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pos = pos % ref.length;
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done = pos == pivot;
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}
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}
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}
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};
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};
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}
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}
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}

‎common/src/test/java/com/tc/util/SimpleRingBufferManualTest.java

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,177 @@
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/*
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* Copyright Terracotta, Inc.
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* Copyright IBM Corp. 2024, 2025
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package com.tc.util;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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/**
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* Manual test class for SimpleRingBuffer that doesn't rely on JUnit
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*/
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public class SimpleRingBufferManualTest {
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public static void main(String[] args) {
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testEmptyBuffer();
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testPartiallyFilledBuffer();
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testFullBufferNoWraparound();
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testWraparoundBuffer();
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testMultipleWraparounds();
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testNullRejection();
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testSingleElement();
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System.out.println("All tests completed!");
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}
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private static void testEmptyBuffer() {
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System.out.println("Testing empty buffer...");
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SimpleRingBuffer<String> buffer = new SimpleRingBuffer<>(5);
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Iterator<String> iterator = buffer.iterator();
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// Empty buffer should have no elements
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if (iterator.hasNext()) {
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System.err.println("FAIL: Empty buffer should not have elements");
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} else {
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System.out.println("PASS: Empty buffer has no elements");
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}
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}
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private static void testPartiallyFilledBuffer() {
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System.out.println("Testing partially filled buffer...");
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SimpleRingBuffer<String> buffer = new SimpleRingBuffer<>(5);
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buffer.put("A");
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buffer.put("B");
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buffer.put("C");
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// Buffer has 3 elements, not wrapped around
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List<String> elements = collectElements(buffer);
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System.out.println("Elements: " + elements);
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if (elements.size() != 3) {
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System.err.println("FAIL: Expected 3 elements, got " + elements.size());
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} else if (!elements.get(0).equals("A") || !elements.get(1).equals("B") || !elements.get(2).equals("C")) {
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System.err.println("FAIL: Elements in wrong order: " + elements);
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} else {
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System.out.println("PASS: Partially filled buffer has correct elements in order");
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}
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}
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private static void testFullBufferNoWraparound() {
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System.out.println("Testing full buffer without wraparound...");
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SimpleRingBuffer<String> buffer = new SimpleRingBuffer<>(3);
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buffer.put("A");
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buffer.put("B");
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buffer.put("C");
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// Buffer is full but hasn't wrapped around
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List<String> elements = collectElements(buffer);
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System.out.println("Elements: " + elements);
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if (elements.size() != 3) {
86+
System.err.println("FAIL: Expected 3 elements, got " + elements.size());
87+
} else if (!elements.get(0).equals("A") || !elements.get(1).equals("B") || !elements.get(2).equals("C")) {
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System.err.println("FAIL: Elements in wrong order: " + elements);
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} else {
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System.out.println("PASS: Full buffer has correct elements in order");
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}
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}
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private static void testWraparoundBuffer() {
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System.out.println("Testing buffer with wraparound...");
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SimpleRingBuffer<String> buffer = new SimpleRingBuffer<>(3);
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buffer.put("A");
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buffer.put("B");
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buffer.put("C");
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buffer.put("D"); // Overwrites A
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// Buffer has wrapped around, D replaced A
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List<String> elements = collectElements(buffer);
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System.out.println("Elements: " + elements);
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if (elements.size() != 3) {
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System.err.println("FAIL: Expected 3 elements, got " + elements.size());
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} else if (!elements.get(0).equals("B") || !elements.get(1).equals("C") || !elements.get(2).equals("D")) {
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System.err.println("FAIL: Elements in wrong order: " + elements);
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} else {
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System.out.println("PASS: Wrapped buffer has correct elements in order");
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}
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}
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private static void testMultipleWraparounds() {
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System.out.println("Testing buffer with multiple wraparounds...");
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SimpleRingBuffer<String> buffer = new SimpleRingBuffer<>(3);
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buffer.put("A");
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buffer.put("B");
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buffer.put("C");
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buffer.put("D"); // Overwrites A
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buffer.put("E"); // Overwrites B
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buffer.put("F"); // Overwrites C
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// After multiple wraparounds
126+
List<String> elements = collectElements(buffer);
127+
System.out.println("Elements: " + elements);
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if (elements.size() != 3) {
130+
System.err.println("FAIL: Expected 3 elements, got " + elements.size());
131+
} else if (!elements.get(0).equals("D") || !elements.get(1).equals("E") || !elements.get(2).equals("F")) {
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System.err.println("FAIL: Elements in wrong order: " + elements);
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} else {
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System.out.println("PASS: Multiple wraparound buffer has correct elements in order");
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}
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}
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private static void testNullRejection() {
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System.out.println("Testing null rejection...");
140+
SimpleRingBuffer<String> buffer = new SimpleRingBuffer<>(3);
141+
try {
142+
buffer.put(null);
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System.err.println("FAIL: Should have thrown NullPointerException");
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} catch (NullPointerException e) {
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System.out.println("PASS: Null was rejected with NullPointerException");
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}
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}
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private static void testSingleElement() {
150+
System.out.println("Testing single element buffer...");
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SimpleRingBuffer<String> buffer = new SimpleRingBuffer<>(1);
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buffer.put("A");
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buffer.put("B"); // Overwrites A
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List<String> elements = collectElements(buffer);
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System.out.println("Elements: " + elements);
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if (elements.size() != 1) {
159+
System.err.println("FAIL: Expected 1 element, got " + elements.size());
160+
} else if (!elements.get(0).equals("B")) {
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System.err.println("FAIL: Expected element B, got " + elements.get(0));
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} else {
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System.out.println("PASS: Single element buffer contains only the newest element");
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}
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}
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// Helper method to collect all elements from the buffer into a list
168+
private static <T> List<T> collectElements(SimpleRingBuffer<T> buffer) {
169+
List<T> result = new ArrayList<>();
170+
for (T element : buffer) {
171+
result.add(element);
172+
}
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return result;
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}
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}
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// Made with Bob

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